It is the objective of this study to test the usefulness of a rigorous analytical technique (Fourier Analysis) for the characterization of the physical state of the coronary arterial bed. From the Fourier analysis of the coronary pressure and flow waveforms, ensemble averages, transfer functions and input impedance will be calculated. These data will allow the coronary bed to be characterized by an epicardial inductance, capacitance and resistance and a time varying endocardial resistance. The coronary arterial bed will be characterized under normal conditions, reactive hyperemia and pharamacological intervention (e.g., epinephrine, nitroprusside, isoprotereral, dobutamine). The above studies will be repeated in the chronically collateralized coronary bed. The coronary vascular tree will be characterized quantitatively in terms of epicardial inductance, capacitance and resistance and endocardial resistance. Effects of pharmacological agents on coronary blood flow may then be assigned to alterations in one or more than one of these parameters. The characterization of the coronary bed with its highly pulsatile waveform will be conducted in the frequency domain as opposed to the traditional approach of simply calculating "mean resistance" from mean pressure and mean flow.